Multistage compressor



June'28, 1949. ug 2,474,410

HULTISTGE COMPRESSOR Filed nee. 8, 1945 Tlcll. I T 3 25 r31 0 a, '1 26 a INVENTOR face A05.

ATTORNEY sure ratios.

passage from one *stage into thenext is effected Patented June 28, 1949 MULTIQSTAGE COMPRESSOR Georg Aue, Winterthur, Switzerland, assignor to Sulzer Freres, Societe Anonyme, Winterthur,

Switzerland Application December 8, 1945, Serial No. 633,745- n In Switzerland January 13, 1945 The present invention relates to a multi-stage compressor in which at least one impeller is provided with blades for working with high peripheral speeds and for obtaining high stage-pres- .The invention consists in that the through a cooler, which is arranged within the compressor casing and forms an organic unit with at least one compressing stage.

With multi-stage compression it is known to recool the compressing medium between separate stages in order to avoid on the one hand impermissible increases of temperature in the medium delivered and in the machine, and on the other hand to reduce the power required for compre ss' ing. According to known proposals the intermediate cooling is effected in such a way that an intermediate cooler of a size which will ensure the requested cooling elTected is builton tothe compressor, or, as a separate aggregate from the com pressor, is inserted between each two stages of the compressor by Tmeans of pipes. It is then evident that the saving of space and weight obtained in any case with centrifugal compressors with high-stage pressure ratios is again cancelled to a large extent by adopting such separate intermediate coolers.

Also the known jacket-cooling adopted with slow-speed centrifugal compressors, which makes use of a double-walled compressor casing with hollow cooling spaces lying between them, cannot prove to be satisfactory in consequence of the surface being necessarily of modest dimensions for carrying away comparatively great quantities of heat, such as are produced in compressors with high and super-high stage-pressure ratios.

These draw-backs can be avoided with the present invention. As compared with the compressors mentioned with known form of coolers,-,

the multi-stage compressor accordingto the invention can be built for the service much lighter; at less cost, and taking up less room. In order to give a comparison, it is mentioned that-assuming equal output and the same pressure ratiothe dimensions for a reciprocating compressor are 3 m. x 3 m. x 1 m., for a slow-speed radial compressor 1.8 m. x 1.2 m. x 1.2 m., and for a two-stage. compressor according to the invention only 0.8 m. x 0.8 m. x 0.7 m. The last mentioned is particularly suitable for producing compressed air in workshops, steel works, mines, and

pressing gases and vapours in chemical processes.

6 Claims. (Cl. 230 -209) Examples of execution of the-subject matter of the invention are illustrated by way of example in the accompanying drawing, where 1 Fig. 1 shows a first form of execution, in axial cross-section,

Fig. '2 a second form of execution. in axial cross-section, and i Fig. 3 a view of the impellerwith the casinghalf removed, and partly in section on the line 5 also for the production of power gas and for building into gas turbine plants and also for com III-III of Fig.2. v

Fig. 4 is a section along line IV-IV of the compressorunit according to the invention illustrated in Fig. 2.

In the example of execution shown in Fig. 1,

-the impeller .body I is fitted with two impeller wheels 2, 2' carrying blades 3, 3 which have a radial extension in cross-section normal to the impeller axis 4 at least in the zones lying at some distance from the axis 4, In this way the blades 3, 3' are prevented from being subjected in these zones to additional bending stresses, subjected as they are to a considerable stressing from centrifugal forces, running at high peripheral speeds of, for instance 300 m./s. and more, as is necessary for the highest stage-pressure ratios of 1.5 and more, referred to atmospheric air. At both ends the impeller body I is carried in the bearing positions 5, and at one end is coupled to 'the driving shaft 6. The impeller body 1 is surrounded by a casing which consists of an inlet part I, a deviating part or chamber 8 and an outlet spiral 9. In the deviating part 8 of the casing the annular-shaped intermediate cooler l0 surrounding the cone shaped impeller wheel 2' is built in and may consist for instance of a pipe coil conducting the cooling medium and surrounding the impeller wheel 2 of the second stage annularly, its beginning l6 and end ll' leading out of the compressor casing and being connected to supply and return piping for cooling medium (not shown in the drawing).

The medium delivered, for instance atmospheric air, is drawn-in in the direction of the arrow II and precompressed by the impeller blades 3 and the difiusor 12 following them. From the diffusor l2 the mediumpasses through the diverting part 8 and the intermediate cooler ill in the direction of the arrow l3, and then flowstemperature of the medium flowing in to-the sec- 0nd stage is reduced approximately to coolingwater temperature, whereby a reduction of the duction of the power required for the compression in the upper stage. At the same time the specific. gravity of the medium handled is correspondingly increased, which causes an increase in the stage-pressure ratio in the upper stage.

According toFigs. 2 and 3v two pressure stages are provided on the double cone shaped'impeller body 38 in such a way that each side of it is fitted with blades 39 and 39', which form the low-pres: sure and high-pressure stages respectively. These blades-39and 39' extend in a screw-line form from the impeller inlet to the impeller outlet, in the direction of rotation opposite ,to the direction ,of rotation l8 of the propeller, and make at the outletwith the peripheral tangent 40 of the impeller 38 and angle on whose cosine is greater than the ratio of the velocity of flow between'blade 39 and 39' to the doubled peripheral speed of the'blades at the outlet. The impeller 38 is carried atboth ends in the bearing positions I 9 of the compressor casing 2 l' and coupled to the driving shaft 20. The part of thecasing 2| surrounding the low-pressure part of the impeller 38 is made with double walls in such a way that the medium,- drawn-in in the direction'of the arrows 22 through the passages 23, lying between the blades 39, flows into the diffuser 24 and is diverted inwardly in the direction of the arrow 25 in the outer chamber 26in the casing. From here, the

medium passes into the inner hollow space 21 of the casing, from where the passages 28 formed by, the wallsof the diffusors 24- lead into the hollow space 29 of the part of the casing 2| sur- 3 or more stages on one and' the same impeller bodyand to provide them with intermediate cooling-built as anorganic unit together with the compressor.

I claim: r l. A multistage compressor comprising an impeller body having a cone shaped surface portion, vanes extending from said surface portion, a substantially cylindrical pressure casing surrounding said surface portion and forming an annular chamber of substantially triangular radial sectional configuration, and substantially annular cooling means disposed in said chamber and extending around the axis .of rotation of said impeller body.

rounding the high-pressure part of the impeller 38. In the annular chamber 29 the medium is diverted in the direction of the arrow 33 and led tothe high-pressure part of the compressor. It flows between the blades 39' and in the direction of the arrow 3| through the diffusor 30 into the spira1 32 and from there passes through the delivery branch 34 to the points of use.

' The intermediate cooler, consis ample of a pipe coil 35, is divided into two parts, one of which is located in the hollow space 26 of the first stage, and the other in the hollow space 29 of the second stage, the two parts surrounding the impeller body 38 annularly. The cooling medium is led to the pipe coil of the intermediate cooler 35 at theinlet position 36 and leaves it at the outlet position 3].

The tubecoil forming the cooling surface in chamber 29 is illustrated in Fig. 4 of the draw- I ings; It is made of semicircular tubes 4| and H the ends of which are rolled into plates 42 and 42" respectively, which plates are adjacent the flange plane 43 of the pressure casing 44,. The individual tubes are interconnected to form a continuous coil upon assembly of the casing.

a further compressing stage, formed for in-' stance as a reciprocating or rotary piston compressor. It'would also be possible, making use or ting for ex- 2. A multistage compressor as defined in claim 1, said cooling means consisting of tube spirals.

having the axis of rotation of said impeller as a center.

' 3. A multistage compressorcomprising an impeller body comprising a plurality of cone shaped surface portions, vanes extending from said surface portions, a substantially cylindrical pressure casing surrounding said surface portions and forming annular chambers of substantially triangular radial sectional configuration, and substantially annular cooling means disposed in said chambers'and extending around the axis of rotation of said impeller body. a

4.'A multistage compressor comprising a body double cone shaped impeller body in which. the.

two cones have a common base ,area, vanes extending from both cone surface-s of said body, a pressure casingsurrounding said body and forming annular. chambers of substantially triangular radial sectional configuration, and substantially annular cooling means disposed in said chambers and extending around the axis of rotation of said impeller body.

5. A multistage compress-or comprising a double cone shaped impeller body in which the two cones have a common base area, vanes extending from both cone suriaces of said body and forming compressing channels having outlet portions-at the large diameter portion of said 'body, a pressure casing surrounding said body and forming annular chambers having inlet portions adjacent the large diameter portion of said body and being connected for compressed medium flow with the outlet portions of said channels, and having outlet portions adjacent the small diameter portions of said body, the outlet portion of one of said annular chambers being connected for compressed medium flow with the inlet portion of the other of said chambers, and substantially annular cooling means disposed in said chambers and extending around the axis of rotation of said impeller body.

6. A multistage compressor comprising a double cone shaped impeller body in which the two cones have a common base area, vanes extending from both cone surfaces of said' body, cone shaped wall portions surrounding said body adjacent said vanes and forming therewith channels having outlet portions at the large diameter portion of said body, a pressure casing surrounding said body and forming annular chambers radially outside of said wall portions and having inlet portions adjacent the large diameter portion and outlet portions adjacent the small diameter portion of said body, a second cone shaped wall portion disposed inside one of said chambers and being spaced from and surrounding one of said first wall portions and formthe form of execution shown in Fig. 1, to provide ing a conduit connected for compressed medium flow at its small diameter end with the outlet portion of the chamber in which it is placed and being connected for compressed medium flow at its large diameter end with the inlet portion of the other chamber, and substantially annular cooling means disposed in said chambers and eX- tending around the axis of rotation of said impeller body.

GEORG AUE.

REFERENCES CITED The following references are of record in the file of this patent: 

